Following the cessation of drilling operations, completions may be initiated in which downhole tubulars and equipment are installed to enable the safe and efficient production from an oil or gas well. During completions, sections of casing or pipe string may be placed into the wellbore to enhance wall strength and minimize the chances of collapse, burst, or tensile failure. Well casings of various sizes may be used, depending upon depth, desired hole size, and types of geological formations encountered. The casing and other tubulars may, in some instances, be stabilized and bonded in position using various physical and chemical techniques.
When cement or other settable compositions are used to stabilize completion equipment, a portion of the drilling fluid may be removed from the wellbore so that the casings may be cemented in place. Primary cementing operations may fill at least a portion of the annular space between the casing and the formation wall with a hydraulic cement composition. The cement composition may then be allowed to solidify in the annular space, thereby forming an annular sheath of cement. During stimulation (such as hydraulic fracturing or other techniques), cement may provide an impermeable barrier that prevents the migration of stimulation fluids between zones to be stimulated in the wellbore. In some cases, when needed, cement may provide an impermeable barrier that prevents the migration of undesired fluids and gases (e.g., water) between zones penetrated by the wellbore during production. Other situations arise where cementing particular zones within a formation may be beneficial. For example, cementing operations may also include use of cement during remediation of lost circulation or zonal isolation.